Regulation of transcription by RNA polymerase II in mammalian cells will be studied at the biochemical level. Advances in the analysis of this fundamental process will be used to elucidate the molecular nature of control of malignant growth. Activation of transcription by sequence- specific transcription factors alters the structure of a basal complex composed of at least the IIA IID factors. The unique aspect of this complex which specifies an increase rate of initiation will be determined. Transcription factors interact with basal factors through specific protein-protein contacts. The chemical nature of these protein signals will be elucidated and the surfaces of the basal factors contacted will be identified. Results from the analysis of yeast suggest that polymerase II associates with the IIA IID complex as a holoenzyme containing other basal factors and cellular components. Evidence for a similar holoenzyme will be sought in mammalian systems. The Oct-1 and Oct-2 transcription factors bind the same octamer sequence but have different essential roles during B cell development. Retroviral vectors will be used to introduce chimeras of Oct-1 and Oct-2 to determine the protein signals which determine their unique roles in B cells. A protocol for the rational design of a sequence-specific transcription factor which will regulate in a dominant fashion a specific endogenous gene has been proposed. This protocol depends upon covalent linkage of sequence-specific domains to maximize affinity and specificity. The technology will be extended and tested by variation of the linker sequences joining the sequence-specific domains, mutation of the binding specificity of the zinc finger domains and fusion of other DNA binding domains. This methodology will be tested by designing a dominant factor which will stimulate or suppress transcription of c-Myc and other genes. Many oncogenes and tumor suppressor genes encode proteins which bind DNA and regulate transcription. In vitro and in vivo assays will be used to study the transcriptional activities of c-Myc, Rb-E2F type complexes and the Wilms' tumor factor-type factors.